12 min · Beginner
Prompt Anatomy: Role, Context, Task, Constraints, Output
A usable first answer starts with a brief: role, context, one task, constraints you can check, and the shape of the output.
Learning objectives
- Name the five parts of RCTCO and the job each part does in a brief.
- Write one prompt that carries a real stance, facts, a single verb, limits, and an output shape.
- Explain why a costume role does not create real expertise or a professional license.
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Why this matters
Most weak chats fail before Gemini answers, because the brief never said who the work is for or what done looks like. RCTCO gives you a stable order so you stop hoping a clever sentence will replace missing facts. You will use the same order on email, study notes, and decisions, and you will still check anything that matters.
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Concept
RCTCO — role, context, task, constraints, and output — is a briefing order, not a spell. Role — the working stance you want, such as a skeptical editor or a career coach. That stance decides what to protect and whose time is scarce. It is not a costume for fun. Pretending Gemini is a famous specialist does not create a license or real expertise. Name the review job, then put the facts in context.
Context — the facts Gemini cannot see: audience, country, decisions already made, and what you already tried. The model cannot see your files unless you paste or upload them, and it does not know your last meeting. Say the reader, the place, and the limit you already chose. If a long version failed, say so, so the next draft does not repeat it. Leave out secrets you would not hand to a new contractor.
Task — one main verb, such as rewrite, compare, or list. If you pile draft, research, and decide into one line, the answer blurs. Split the pile: finish one verb, then ask for the next in a follow-up. Constraints — limits you can check: length, must-include items, must-avoid items, reading level, and sources you will accept. Prefer under 120 words and no new statistics over a vague try your best. A rule you cannot test is only a wish.
Output — the shape of the answer: a table, headings, a JSON-like list, an email, or five options and then a recommendation. Shape stops a blog post when you needed a memo. Read this worked diagram before you send a brief. Role: skeptical editor. Context: a busy clinic manager in Kenya who rejected a long draft. Task: rewrite the update. Constraints: 120 words, no medical claims, plain English. Output: a subject line plus three short paragraphs.
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Real-world example
Diagram of a clinic update
A community clinic needs a Friday update for a manager who has three minutes. The weak line is Write something about the vaccine day. The brief below uses every RCTCO part. Role: you are a skeptical editor who protects the manager's time. Context: the reader is in Nairobi, the event was Saturday, attendance was 140 people, and yesterday's draft was too long. Task: rewrite the update. Constraints: at most 110 words, include the date and the attendance number, avoid medical advice, and use plain English. Output: a subject line and three short paragraphs labeled What happened, What is next, and What you need. The diagram is the prompt. Nothing in the role makes Gemini a clinician. You still check the number against the register before you send the note.
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Gemini demonstration
A realistic exchange. Open Gemini beside this page and try a version with your own facts.
You
Write something about the vaccine day.
Gemini
That request names a topic and nothing else. I would have to guess the reader, the country, the length, and whether you want an email, a poster, or a list. Those guesses are usually wrong. A usable brief names a stance, the facts I cannot see, one verb, rules you can check, and a shape. Role is missing, so the voice may turn into a brochure. Context is missing, so a city or a result may be invented. The task is only a vague verb. Constraints and output are both absent, so the draft can wander. Paste the date, the audience, and the one number you already trust.
You
You are a skeptical editor who protects a busy reader's time. Context: the reader is a clinic manager in Nairobi. The vaccine day was Saturday. Attendance was 140 people. Yesterday's draft was too long and was rejected. Task: rewrite the update. Constraints: at most 110 words, include the date and the attendance number, no medical claims, plain English, and do not invent figures. Output: a subject line plus three short paragraphs labeled What happened, What is next, and What you need.
Gemini
Subject: Saturday vaccine day, 140 people, one decision needed. What happened: On Saturday the community clinic in Nairobi saw 140 people at the vaccine day. The line moved, and the team finished the session without adding extra hours. What is next: The same desk setup will run again next month, and the register will be checked before any public number is shared. What you need: Please confirm by Tuesday whether the Saturday date stays, because the hall booking closes Wednesday. This draft stays inside 110 words, uses the number you supplied, and makes no medical claim. Please match 140 against the register before you send it.
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Prompt breakdown
The prompt
You are a skeptical editor who protects a busy reader's time. Context: the reader is a clinic manager in Nairobi. The vaccine day was Saturday. Attendance was 140 people. Yesterday's draft was too long and was rejected. Task: rewrite the update. Constraints: at most 110 words, include the date and the attendance number, no medical claims, plain English, and do not invent figures. Output: a subject line plus three short paragraphs labeled What happened, What is next, and What you need.
- Role sets a skeptical editor so the draft protects a busy reader's time, without pretending to be a clinician.
- Context supplies the city, the date, the attendance figure, and the rejected long draft, which Gemini cannot see on its own.
- One task, rewrite, keeps the model from also inventing a campaign plan in the same breath.
- Constraints and the output shape make the draft checkable: length, banned claims, and three labeled paragraphs under a subject line.
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Common mistakes
Usually
You are the world's greatest doctor. Write a fun update.
Better
You are a skeptical editor. Rewrite this update for a clinic manager in Nairobi. No medical claims.
Usually
Draft the update, research other clinics, and decide the budget.
Better
Rewrite this update in 110 words. I will ask for a budget comparison in the next message.
Usually
Make it good and professional.
Better
Use plain English, at most 110 words, include the date and the attendance number, and avoid slogans.
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Practice exercise
Brief one real task with RCTCO
Done when: You have a saved prompt with all five RCTCO parts and a second draft that meets the length and must-include rules.
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Challenge
Diagram a prompt you already sent
Open a chat you sent this week that came back vague or off tone. Copy your original prompt into a note. Mark each sentence R, C, T, Co, or O for the part it tried to do. Circle any part that is missing. Rewrite the prompt as five labeled lines: Role, Context, Task, Constraints, Output. Keep one main verb. Add the audience, the country or language, one length limit, one must-avoid, and the shape you wanted. Run the new brief once. In three lines, say which added part changed the answer most, and which fact you still need to verify yourself before you use the draft.
Hint: If you cannot label a sentence, it is probably a mood, not a part of the brief. Replace it with a rule you can check.
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Key takeaways
- RCTCO is a briefing order: role, context, task, constraints, and output.
- A role is a stance, such as a skeptical editor, not a costume that creates expertise.
- Gemini cannot see your files unless you paste or upload them, so context has to carry the facts.
- One main verb plus a shape you can check beats a pile of jobs in a single line.
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